Answer:
3783
Step-by-step explanation:
I would round 189 to 190 and multiply by 15
190 *15 = 2850
I would round 79 to 80 and multiply 80x 12 = 960
2850 + 960 = 3810 notebooks ( estimated)
actual totals: 15*189 = 2835
12*79 = 948
2835 + 948 = 3783
this estimate was high
depending on the situation depends on if it is better to over estimate or under estimate